I was looking for FJ center caps, but ebay was too expensive (I'm a cheap bastard) and the Toyota dealerships in NC, SC and VA could only get a hold of 3 caps, I looked for a deal online.
I bought the TRD center caps at TRDparts4u. I got these caps for $9.99 each, way cheaper than the $25 a pop for the same part on ebay.
Shipping was $10.
The caps went on without a hitch, and I think that they look awesome. No modification was necassary.
I used a small pry bar to pop off the original center caps. I wrapped the end of my pry bar in tape to prevent scratching up the cap, and pried against a lugnut for leverage.
Here's how it looks: